At present, in an image display device such as a Liquid Crystal Display panel and an Organic electroluminescence Light-Emitting Diode display panel, a pixel unit comprises a Red (R) sub-pixel unit, a Green (G) sub-pixel unit and a Blue (B) sub-pixel unit, and a color image is displayed by controlling the grayscale values of respective sub-pixel units to be blended together to obtain a color as needed to be displayed. Since luminous efficiency of RGB primary colors is relatively low, optimization of the display device being constructed by the RGB primary colors is constrained. In view of the above, a pixel unit comprising a Red (R) sub-pixel unit, a Green (G) sub-pixel unit, a Blue (B) sub-pixel unit and a White (W) sub-pixel unit is developed to improve the luminous efficiency of a RGB display.
Currently, in a conversion from RGB signals into RGBW signals, many reasons can cause shifting of four colors R, G, B, W, which may result in that an actual color gamut is different than a color gamut expected at design, and cause problems of color gamut lose and color distortion. Therefore, how to improve accuracy of color gamut in a conversion from RGB signals into RGBW signals is a technical problem that those skilled in the art need to solve urgently.